Sources of Atmospheric Mercury Deposition

1. Where Does the Mercury in AtmosphericMercury Deposition Come From? Mark Cohen, Winston Luke, Paul Kelley, Richard Artz NOAA Air Resources Laboratory Silver Spring, Maryland http://www.arl.noaa.gov/mercury.php Gulf of Mexico Alliance Mercury Workshop December 2-4, 2008, Gulfport, Mississippi

2. Acknowledgements • Jake Walker, Mark Woodrey, Glen Ruple (Grand Bay National Estuarine Research Reserve) • Prof’s Yerramilli Anjaneyulu, Jerzy Lesczcynski, Hari Dasari, & many colleagues(Jackson State Univ.) • Durwin Carter (U.S. Fish and Wildlife Service -- Grand Bay National Wildlife Refuge) • Steve Brooks (NOAA ATDD and Canann Valley Institute) • Roland Draxler, Glenn Rolph, Barbara Stunder, Steve Fine (NOAA Air Resources Laboratory) • David Schmeltz, Tim Sharac, Rick Haeuber, Sam Napolitano (US EPA Clean Air Markets Division) • Gary Matlock, Russell Callender, Jawed Hameedi (NOAA NOS Nat’l Centers for Coastal Ocean Science)

3. Different “forms” of mercury in the atmosphere • Elemental Mercury -- Hg(0) • most of total Hg in atmosphere • not very water soluble • doesn’t easily dry or wet deposit • upward evasion vs. deposition • atmos. lifetime approx ~ 0.5-1 yr • globally distributed Atmospheric methyl-mercury? • Reactive Gaseous Mercury -- RGM • a few percent of total atmos Hg • oxidized Hg (HgCl2, others) • operationally defined • very water soluble and “sticky” • atmos. lifetime <= 1 week • local and regional effects • bioavailable • Particulate Mercury -- Hg(p) • a few percent of total atmos Hg • not pure particles of mercury • Hg compounds in/on atmos particles • species largely unknown (HgO?) • atmos. lifetime approx 1~ 2 weeks • local and regional effects • bioavailability?

4. Hg from other sources: local, regional & more distant Reactive halogens in marine boundary layer emissions of Hg(0), Hg(II), Hg(p) •  Enhanced oxidation of Hg(0) to RGM • Enhanced deposition wet and dry deposition to the watershed wet and dry deposition to the water surface

5. size/shape of symbol denotes amount of mercury emitted (kg/yr) 5 - 10 10 - 50 50 - 100 100 – 300 300 - 500 500 - 850 color of symbol denotes type of mercury source coal-fired power plants other fuel combustion waste incineration metallurgical manufacturing & other Reactive Gaseous Mercury (RGM) Emissions to the Air 2002 U.S. data from USEPA National Emissions Inventory (NEI); 1999 Mexican data from inventory prepared by Acosta y Asociados for the Commission for Environmental Cooperation

6. size/shape of symbol denotes amount of mercury emitted (kg/yr) 5 - 10 10 - 50 50 - 100 100 – 300 300 - 500 500 - 1000 1000 - 3500 color of symbol denotes type of mercury source coal-fired power plants other fuel combustion waste incineration metallurgical manufacturing & other Elemental Mercury -- Hg(0) -- Emissions to the Air

7. Why are emissions speciation data - and potential plume transformations -- critical? Logarithmic NOTE: distance results averaged over all directions – Some directions will have higher fluxes, some will have lower

8. Wet Deposition Sites Atmospheric Mercury Measurement Site MDN - 2007 at the Grand Bay NERR, MS Pensacola Wet Dep Study (Event-Based) Speciated Ambient Concentration Sites Existing Long-Term Sites view from top of the tower FL – TMDL (planned) Previous & Other size/shape of symbol denotes amount of mercury emitted (kg/yr) 5 - 10 10 - 50 50 - 100 100 – 300 mercury and trace gas monitoring tower (10 meters) 300 - 500 500 - 850 color of symbol denotes type of mercury source coal-fired power plants other fuel combustion waste incineration metallurgical manufacturing & other RGM Emissions and Atmospheric Hg Measurement Sites

9. Monitoring Site NOAA SEARCH USGS UWF/FSU MDN type of mercury emissions source coal-fired power plant waste incinerator manufacturing total atmospheric mercury emissions (kg/yr, 1999 EPA NEI) metallurgical other fuel combustion 1 – 50 50 - 100 100 - 200 200 - 400 Mississippi Alabama Barry MS 22 paper manuf paper manuf AL02 Pascagoula MSW incin Mobile Molino Crist Victor J. Daniel Holcim Cement Pace OLF haz waste incin Ellyson AL24 Weeks Bay Mobile Bay Jack Watson Pascagoula NOAA Grand Bay NERR Hg site

10. > 1000 ug/m2-yr > 10 ug/m2-yr > 0.1 ug/m2-yr > 0.001 ug/m2-yr one Hg emissions source Model-predicted mercury deposition (wet + dry) in the vicinity of one example Hg source for a 1 week period in April 2008 Gulfport Grand Bay NERR monitoring site two-hour deposition values converted to annual equivalent

11. > 1000 ug/m2-yr > 10 ug/m2-yr > 0.1 ug/m2-yr > 0.001 ug/m2-yr one Hg emissions source Model-predicted mercury deposition (wet + dry) in the vicinity of one example Hg source for a 1 week period in April 2008 Gulfport Grand Bay NERR monitoring site two-hour deposition values converted to annual equivalent Large, time-varying spatial gradients in deposition & source-receptor relationships

12. Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Recent RGM concentrations measured at the Grand Bay NERR Then down for ~2 months due to hurricanes …. …. 2007 2008

13. Atmospheric Mercury Modeling for the Gulf of Mexico region examples of recent, current, and planned work

14. Total mercury deposition in the Gulf of Mexico region (ca. mid to late 1990’s) estimated by the EPRI TEAM-Hg model, coupled with a global chemical transport model (micrograms per square meter, 100 km grid) Seigneur, C., et al. (2004). Global Source Attribution for Mercury Deposition in the United States. Environ. Sci. Technol.38, 555-569 Atmospheric Mercury Modeling for the Gulf of Mexico region examples of recent, current, and planned work

15. Atmospheric Mercury Modeling for the Gulf of Mexico region examples of recent, current, and planned work

16. Total mercury deposition in the Gulf of Mexico region for 2001 estimated by the USEPA-NOAA CMAQ-Hg model (micrograms per square meter, 36 km grid) Image and modeling results courtesy of Russ Bullock, USEPA, based on modeling analysis done for the Clean Air Mercury Rule

17. Atmospheric Mercury Modeling for the Gulf of Mexico region examples of recent, current, and planned work

18. Figure 6-3c. Simulated Annual Mercury Deposition (g km-2) for the REMSAD 12-km Modeling Domain (with Average Boundary Conditions): Total (Dry + Wet) Deposition. Model-Based Analysis And Tracking Of Airborne Mercury Emissions To Assist in Watershed Planning. August 2008, Watershed Branch (4503-T), Office of Wetlands, Oceans, and Watersheds, U.S. EPA, Washington, DC. http://www.epa.gov/owow/tmdl/pdf/final300report_10072008.pdf

19. Atmospheric Mercury Modeling for the Gulf of Mexico region examples of recent, current, and planned work

20. Atmospheric Mercury Modeling for the Gulf of Mexico region examples of recent, current, and planned work

21. 1996 meteorology (NGM) • 1999 U.S. emissions (EPA NEI) • 2000 Canadian emissions (Envr. Canada) • no sources other than U.S. & Can. anthropogenic emissions • total modeled deposition to Mobile Bay ~ 3.5 g Hg/km2-year Largest Modeled Individual Sources Contributing Mercury Deposition Directly to Mobile Bay (large regional view) 21

22. 1996 meteorology (NGM) • 1999 U.S. emissions (EPA NEI) • 2000 Canadian emissions (Envr. Canada) • no sources other than U.S. & Can. anthropogenic emissions • total modeled deposition to Mobile Bay ~ 3.5 g Hg/km2-year Largest Modeled Individual Sources Contributing Mercury Deposition Directly to Mobile Bay (local view) 22

23. Top 25 Modeled Contributors to 1999 Hg Deposition Directly to Mobile Bay, considering anthropogenic direct emission sources in the United States and Canada Cumulative Fraction of Modeled Deposition 23

24. Atmospheric Mercury Modeling for the Gulf of Mexico region examples of recent, current, and planned work • All models have evolving strengths and weaknesses… • Others? (this may not be a complete list…) • Collaboration? (e.g., emissions inventories, model intercomparisons)

25. What Do We Need to Know Regarding Atmospheric Mercury? * consistent with the needs of subsequent analyses (e.g., ecosystem modeling) with respect to spatial, temporal, and “species” resolution (e.g., Hg(0) vs. RGM vs. Hg(p))

26. Can we learn what is needed about atmospheric mercury deposition by making atmospheric measurements alone? NO…

27. Hey, you got modeling in my monitoring! To get the answers we need, we need to use both monitoring and modeling -- together Hey, you got monitoring in my modeling! Modeling needed to help interpret and extend measurements and to estimate source-receptor relationships Monitoring needed to provide solid deposition estimates at a given location and for model development and evaluation

28. Models are not perfect “…Everyone believes monitoring results except for the person making the measurements… and nobody believes modeling results except for the person doing the modeling…” How not perfect are they? Results are encouraging, but difficult to evaluate models due to lack of contemporaneous monitoring and emissions inventory data Models are a test of our knowledge… If they don’t work, fundamental things about our understanding of atmospheric mercury that are wrong or incomplete… More certain info at a few locations (monitoring) vs. less certain info region-wide (modeling)

29. Conclusion Since we need to know how much atmospheric Hg deposition there is and where it comes from, we need both models and measurements Two Suggestions 1. The Gulf of Mexico Alliance Action Plan should identify the role of models explicitly 2. A critical need – one deserving its own high priority “action item” – is for collaboration between stakeholders to improve the mercury air emissions inventory in the region

30. Thanks!

31. Extra Slides

32. Inputs to Model For model evaluation, emissions and meteorology must be for the same time period as ambient measurement data meteorology emissions Atmospheric Mercury Model atmospheric chemistry wet deposition phase partitioning surface exchange Model Evaluation Speciated ambient concentration data Wet deposition data Model Outputs Wet and dry deposition of different Hg forms to Gulf of Mexico & watershed Source attribution information for deposition 32

33. Atmospheric Mercury Modeling for the Gulf of Mexico region examples of recent, current, and planned work • Others? • Collaboration? (e.g., emissions inventories, model intercomparisons)

35. deposition (ug/m2)* Beltsville monitoring site 100 - 1000 10 – 100 1 - 10 0.1 – 1 Washington D.C. Model-predicted hourly mercury deposition (wet + dry) in the vicinity of one example Hg source for a 3-day period in July 2007 one Hg emissions source * hourly deposition converted to annual equivalent

36. deposition (ug/m2)* Beltsville monitoring site 100 - 1000 10 – 100 1 - 10 0.1 – 1 Washington D.C. Model-predicted hourly mercury deposition (wet + dry) in the vicinity of one example Hg source for a 3-day period in July 2007 one Hg emissions source * hourly deposition converted to annual equivalent

37. Large, time-varying spatial gradients in deposition & source-receptor relationships deposition (ug/m2)* Beltsville monitoring site 100 - 1000 10 – 100 1 - 10 0.1 – 1 Washington D.C. Model-predicted hourly mercury deposition (wet + dry) in the vicinity of one example Hg source for a 3-day period in July 2007 one Hg emissions source * hourly deposition converted to annual equivalent

38. Earlier Modeling Results For Mobile Bay

39. 1996 meteorology (NGM) • 1999 U.S. emissions (EPA NEI) • 2000 Canadian emissions (Envr. Canada) • no sources other than U.S. & Can. anthropogenic emissions • total modeled deposition to Mobile Bay ~ 3.5 g Hg/km2-year Largest Modeled Individual Sources Contributing Mercury Deposition Directly to Mobile Bay (national view) 39

40. 1996 meteorology (NGM) • 1999 U.S. emissions (EPA NEI) • 2000 Canadian emissions (Envr. Canada) • no sources other than U.S. & Can. anthropogenic emissions • total modeled deposition to Mobile Bay ~ 3.5 g Hg/km2-year 40

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44. Other Model Results

45. Total mercury deposition in the Gulf of Mexico region for 2001 estimated by the USEPA-NOAA CMAQ-Hg model (micrograms per square meter, 36 km grid) Image and modeling results courtesy of Russ Bullock, USEPA, based on modeling analysis done for the Clean Air Mercury Rule

46. Total mercury deposition in the Gulf of Mexico region (ca. mid to late 1990’s) estimated by the EPRI TEAM-Hg model, coupled with a global chemical transport model (micrograms per square meter, 100 km grid) Seigneur, C., et al. (2004). Global Source Attribution for Mercury Deposition in the United States. Environ. Sci. Technol.38, 555-569

47. Figure 6-3c. Simulated Annual Mercury Deposition (g km-2) for the REMSAD 12-km Modeling Domain (with Average Boundary Conditions): Total (Dry + Wet) Deposition. Model-Based Analysis And Tracking Of Airborne Mercury Emissions To Assist in Watershed Planning. August 2008, Watershed Branch (4503-T), Office of Wetlands, Oceans, and Watersheds, U.S. EPA, Washington, DC. http://www.epa.gov/owow/tmdl/pdf/final300report_10072008.pdf